Geometry-free Stochastic Analysis of BDS Triple Frequency Signals

Yongchao Wang, Yanming Feng, Fu Zheng

Peer Reviewed

Abstract:	The paper presents a geometry-free approach to assess the variation of covariance matrices of undifferenced triplefrequency GNSS measurements and its impact on positioning solutions. Four independent geometryfree/ionosphere-free (GFIF) models formed from original triple-frequency code and phase signals allow for effective computation of variance-covariance matrices using real data. Variance Component Estimation (VCE) algorithms are implemented to obtain the covariance matrices for three pseudorange and three carrier-phase signals epoch-by-epoch. Covariance results from the triple frequency Beidou System (BDS) and GPS data sets demonstrate that the estimated standard deviation varies in consistence with the amplitude of actual GFIF error time series. The single point positioning (SPP) results from BDS ionosphere-free measurements at four MGEX stations demonstrate an improvement of up to about 50% in Up direction relative to the results based on a traditional elevation weighting model in terms of root mean square statistics. Additionally, a more extensive SPP analysis at 95 global MGEX stations based on GPS ionosphere-free measurements shows an average improvement of about 10% relative to the traditional results. This finding provides a preliminary confirmation that adequate consideration of the variation of covariance leads to the improvement of GNSS state solutions.
Published in:	Proceedings of the 2016 International Technical Meeting of The Institute of Navigation January 25 - 28, 2016 Hyatt Regency Monterey Monterey, California
Pages:	956 - 969
Cite this article:	Wang, Yongchao, Feng, Yanming, Zheng, Fu, "Geometry-free Stochastic Analysis of BDS Triple Frequency Signals," Proceedings of the 2016 International Technical Meeting of The Institute of Navigation, Monterey, California, January 2016, pp. 956-969. https://doi.org/10.33012/2016.13475
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